Rigid and semi-rigid strips, such as test strips are used extensively in chemical analysis and medicine. For example, test strips are used to check for chemical concentrations or contaminants in water chemistry. In medicine, diagnostic test strips are used to measure analyte concentrations in biological fluids. Diagnostic test strips are commonly used by diabetics to monitor their blood glucose levels.
Such test strips are moisture sensitive and need to be protected from contaminants and maintained at appropriate humidity levels. They are usually stored in moisture resistant, polymer vials containing some sort of desiccant located in the cap or co-molded in the vial itself. Ideally, to avoid contamination, test strips should not be handled or touched before use.
Some diabetics have to check their blood glucose levels multiple times a day. The test strips are slippery and only a few millimeters in width and length. Due to the disease, diabetics may have diminished feel and eyesight. It is difficult for even those with good dexterity and eyesight to quickly extract a single test strip from a small vial that may contain up to 50 strips. The usual method requires inserting a finger into the vial to attempt sliding out a single strip, or tilting or shaking the vial to allow the test strips to slide half way out so a single test strip may be grasped and removed. These methods often lead to several test strips being touched and possibly contaminated by skin oils, etc. The test strips are also likely to fall out of the vial, damaging them or exposing them to dust and other contaminants. If returned to the vial, the contaminated strips could cross-contaminate the remaining strips. Also, the time required to manually grasp and remove a single test strip can allow the infiltration of airborne contaminants and moist ambient air into the open mouth of the usual vial container. This can degrade the reagent in the strips, compromising the quality of future tests. Such containers also commonly contain a desiccant, and the inadvertent intake of moisture can reduce its effective life.
Several complex test strip dispensers have been created to try to overcome some of the disadvantages associated with the simple test strip vials described above (see for example U.S. Pat. No. 5,489,414 to Schreiber et al; U.S. Pat. No. 5,510,266 to Bonner et al; U.S. Pat. No. 5,854,074 to Charlton et al and U.S. Pat. No. 5,989,917 to McAleer et al.) However, due to the complexity of these and other designs, the high cost of manufacture and assembly can put these devices out of the reach of the average user. Some more recent devices have been developed to try to reduce the number of required components, thereby lowering manufacturing costs (see for example U.S. Pat. No. 6,872,358 to Hagen et al; U.S. Pat. No. 7,172,728 to Otake; U.S. Pat. No. 7,597,853 to West et al; U.S. Pat. No 7,628,292 to Lancesseur et al; and U.S. Pat. No. 7,670,562 to Sacherer).
However, these devices suffer from certain disadvantages. Although the number of parts has been reduced, several are still mechanically complex and require considerable assembly of small parts. Most fail to maintain a constant moisture-free environment. Specifically, every time the caps and bases are separated to dispense a test strip, moisture and possible airborne contaminants are allowed, to some degree, to contact the test strips within. When the caps are replaced, the moisture inside the dispenser is sealed in and remains until the desiccant, if present, adsorbs it. These devices also fail to provide a means of monitoring the condition of the desiccant. If re-useable, most fail to describe the desiccant's eventual replacement. It is also difficult to determine the number of strips remaining inside the devices. And most provide no visual confirmation that a test strip has actually been selected until the cap is removed. Those that are reusable don't appear to be easily reloaded by the end user, or reloaded without touching and exposing the strips to outside contamination.
As a result, there continues to be a need for a simple, inexpensive device to singulate and dispense one at a time, rigid and semi-rigid strips such as test strips which are simple and inexpensive to manufacture, which maintain the integrity of their contents, are simple to reload, and have provision for an easily replaced desiccant.